Abstract: A rotary encoder capable of detecting angular rotation of a rotating shaft, and identifying its neutral position without the need for multiple encoder wheels. A magnetoresistive sensor is positioned adjacent the periphery of a single multipole magnet ring attached to a steering wheel shaft. The magnet ring comprises alternating N-pole and S-pole magnetic regions along its periphery, the surface of one of the regions containing a demagnetized portion. The sensor produces a sinusoidal signal as the shaft is rotated, responsive to the passage of the magnetic regions, with a period equal to the passage of two successive magnetic regions adjacent the sensor. The angular position of the shaft which aligns the demagnetized portion adjacent the sensor corresponds to the shaft's neutral position. Aligning of the demagnetized portion adjacent the sensor causes a voltage irregularity within the sensor's otherwise sinusoidal output signal, which is detected by a signal processing circuit.

Abstract: A power steering unit has an electromagnetic mechanism controlled by a computer-based controller for varying the steering effort in accordance with vehicle speed. The same controller is used to adjust the steering effort in accordance with a calibration value to obtain steering effort uniformity. The calibration value is obtained by applying a force to a vehicle wheel and measuring the resulting torque on the steering wheel (or vice versa) and comparing the resulting force to a standard. Any deviation from the standard is stored in the controller as a correction factor. Alternatively, the characteristics of the steering gear and the power steering pump are measured and encoded on the unit when manufactured and the encoded values are read after assembly in a vehicle and used to calculate the correction factor which is then stored in the controller.

Abstract: A hydraulic power steering system having conventional relatively rotatable spool and valve body elements for flow regulation, and an integral electromagnetic mechanism which effectively varies the centering force between the spool and valve body to adjust the level of steering assist provided for a given operator steering input. The electromagnetic mechanism includes a rotary magnetic circuit and a stationary magnetic circuit. The rotary magnetic circuit comprises a pair of radially displaced magnetic pole pieces which rotate with the input shaft and a permanent magnet ring element which is disposed between the pole pieces and which rotates with the pinion shaft. The stationary magnetic circuit includes an annular exciting coil disposed in proximity to the rotary magnetic circuit. The exciting coil is energized so as to vary the valve body/spool centering force, and hence the driver steering effort, with vehicle speed.

Abstract: A hydraulically assisted power steering system subject to variance in steering effort due to temperature change is compensated to give consistent response at all temperatures. A hydraulic control valve is coupled to an electromagnetic device which controls the steering effort as a function of energization current. The current is adjusted in accordance with temperature to compensate for temperature changes. A microcomputer controller stores empirical data relating to the effect of temperature on steering effort and calculates the current adjustment necessary for any measured system temperature. In one embodiment, the temperature is not measured directly but is derived from the deviation of energization current from the theoretical desired current, which deviation is a function of temperature. The effect of voltage variations is also compensated for.

Abstract: A check valve for disposition between a vacuum operated device and the intake of an auxiliary vacuum pump of an automobile which discharges into the crankcase of the engine of the vehicle. The check valve includes an elastomeric umbrella valve having a flexible lip which is self-biased to a closed position preventing backflow of air to the vacuum operated device and which is flexed to a normal open position by a pressure difference corresponding to pump operation with the integrity of the auxiliary vacuum system intact. A larger pressure difference corresponding to operation of the vacuum pump with the integrity of the auxiliary vacuum system breached flexes the lip of the umbrella valve to a control open position wherein airflow is restricted to only a control orifice of the valve the flow area of which orifice is predetermined to limit airflow to less than the rate at which air is scavenged from the crankcase of the engine.

Abstract: Power steering gear with integral rotary valve for directing hydraulic pressure fluid to and from a piston nut and in which a sector gear actuated plunger provides a drag load on piston nut screw so that the valve body will be grounded and the valve spool will be immediately turned relative to the valve body on rotation of the stub shaft before there is lash take-up between the threads of the piston nut and screw which drivingly connect the valve body to the piston nut and sector gear.

Abstract: Worm to rack piston seal for power steering gear having a resilient cylindrical body with internal thread construction conforming to the profile and lead of the worm for a rack piston nut. During powered right and left turns, the seal is pressure loaded radially for improved fluid sealing and relaxed during low pressure conditions when there is no steering input for improved returnability of the rack piston nut to its centered position.

Abstract: A valve for distributing secondary air from an engine driven pump between the engine exhaust conduit and an accessory device has a valve chamber with an inlet from the air pump and an outlet to the exhaust conduit and a pressure chamber with an outlet to the accessory device and a movable wall biased inward by a spring. A fixed wall between the valve and pressure chambers has a central opening and peripheral openings. A shaft fixed to the movable wall extends through the central opening into the valve chamber and has a valve member on its end for opening and closing the valve chamber outlet. A flexible annular sealing valve member has an inner circular bead sealingly engaging a groove in the shaft, an outer circumferential groove sealingly engaging the periphery of the central opening and an outer peripheral flap valve portion covering the peripheral openings within the pressure chamber to act as a check valve for allowing air flow only from the valve chamber to the pressure chamber.